Fast Failover for Control Traffic in Software-Defined Networks

The Software-Defined Network (SDN) design decouples forwarding and control planes, and runs the controlling functions on servers that might be in different physical locations from the forwarding elements. Such separation introduces new challenges to the network resiliency, because disconnection between switches and the controller could disable the forwarding plane. In this paper, the authors analyze resiliency of the connection between control and forwarding planes in SDN. They propose algorithms to improve this resiliency by maximizing the possibility of fast failover - which they achieve through resilience-aware controller placement and control-traffic routing in the network.